Unexplained recurrent spontaneous abortion (URSA) is a common complication of pregnancy. Although tolerance of the maternal immune system is considered to be essential for a normal pregnancy, the precise mechanism underlying the pathogenesis of URSA remains to be fully elucidated, albeit it is known to involve inflammation. Here, we examine the relationship between the expression of inflammatory cytokines and the activation of downstream signaling pathways in URSA patients. Decidual and peripheral blood samples were collected from 30 URSA patients and from 30 women with normal early pregnancies. Western blot analysis was used to measure the expression levels of signal transducers and activators of transcription 3(STAT3), phosphorylated STAT3(p-STAT3), and interleukin-17 receptor(IL-17R) in the decidual samples. Enzyme-linked immunosorbent assay was used to assess the levels of IL-17, IL-10, IL-6, and IL-23 in the peripheral blood and decidual samples. In the URSA patients, the IL-10 expression levels were lower than those in the control subjects (P<0.05), whereas IL-6, IL-17, and IL-23 were all expressed at higher levels(P<0.05). Furthermore, the expression levels of IL-17R and p-STAT3 were higher in the URSA patients, exhibiting a trend similar to that of IL-23. Our finding of increased IL-23 expression in the deciduae and peripheral blood of patients with URSA suggest that this maybe a contributing factor to the pathogenesis of this disease. Likewise, STAT3 activation through its phosphorylation, which was associated with the IL-23 increase, may also be involved in URSA pathogenesis. However, the precise pathogenic mechanism requires further study.

Objectives Investigation of mechanism related to excessive invasion of trophoblast cells in placenta accreta spectrum disorders (PAS) provides more strategies and ideas for clinical diagnosis and treatment. Materials and Methods Blood and placental samples were collected from included patients. The distribution and expression of CXCL12, CXCR4 and CXCR7 proteins in the paraffin of placental tissue in the included cases were analysed, and we analyse the downstream pathways or key proteins involved in cell invasion. Results Firstly, our results determined that CXCL12 and CXCR4/CXCR7 were increased in extravillous trophoblastic cell (CXCL12: P < .001; CXCR4: P < .001; CXCR7: P < .001), and the expression levels were closely related to the invasion depth of trophoblastic cells. Secondly, CXCL12 has the potential to become a biochemical indicator of PAS since the high expression of placental trophoblast CXCL12 may be an important source of blood CXCL12. Using lentivirus‐mediated RNA interference and overexpression assay, it was found that both chemokine CXCL12 and receptor CXCR4/CXCR7 are associated with regulation of trophoblast cell proliferation, migration and invasion. Further results proved that through the activating the phosphorylation and increasing the expression of MLC and AKT proteins in the Rho/rock, PI3K/AKT signalling pathway, CXCL12, CXCR4 and CXCR7 could up‐regulate the expression of RhoA, Rac1 and Cdc42 proteins to promote the migration and invasion of extravillous trophoblastic cell and ultimately formate the placenta accrete compare to the normal placenta. Conclusions Our research proved that trophoblasts may contribute to a PAS‐associated increase in CXCL12 levels in maternal blood. CXCL12 is not only associated with biological roles of PAS, but may also be potential for prediction of PAS.